Drying apparatus



W. J. JOHNSON. Drying Apparatus.

Patented June 1, 1880.

(V i U Li (NojModeL) NFETERS, FHDTG-LITHOGRAPHER VASHINGT N STATESHATENT rrine@ DRYING APPARATUS.

SPECIFICATION forming` part of Letters Patent No. 228,259, dated June 1,1880.

Application filed .April 8, 1880.

To all whom it may concew:

Be it known that I, WILLIAM J. J oHNsoN, of Boston, in the county ofSuffolk and State of Massachusetts, have invented certain Improvementsin Drying Apparatus, of which the following is a specification.

My invention relates more especially to that class of drying apparatusused in printing establishments for drying the matrices from whichstereotype-plates are cast; and it con` sists in an improved methodwhereby the Work is more perfectly performed than by the ordinarymethod, and with great economy of time, and also in the apparatus forcarrying said method into effect, all of which is heroinafter more fullyset forth and explained, reference being had to the drawingsaccompanying and forming part of this specification, in which- Figure 1shows an elevation, and Fig. 2 a transverse section, of the apparatusembodying my invention.

In most dailynewspaper establishments where the paper has a very largecirculation it is usual to stereotype or reproduce the forms in order todelay going to press as long as possible, and then work off the editionwith sufficient rapidity. The matrices used in casting suchstereotype-plates are produced by taking an impression of the forms bymeans of a pulpy composition applied to the face of the type underpressure, the matrix so produced being afterward carefully dried andremoved.

It is obvious that the whole operation of producing and drying thematrix in this manner and in a limited time must necessarily be a veryrapid one in order to make it available. By the method of dryingordinarily purs'ued the matrices are placed upon a heated bed beforebeing removed from the forms, and are covered with blankets for theabsorption of the moisture, and are then subjected to pressure from anordinary flat press-platen. By this method evaporation is retarded bythe use of the blankets, and vexatious and expensive delays frequentlyoccur on account of the difficulty experienced in drying the matricesproperly and in season.

My invention is designed to obviate these difficulties and to that end Isubject the matrix to the pressure of a cushion of dry com- (No model.)

pressed air in such a manner as to secure a uniform pressure upon allparts of its outer surface, whereby the matrix is kept perfectly flatupon the drying-bed, and thus prevented from warping.

To secure the removal of the moisture evaporated from the matrix, Ipermit a limited escape of the compressed air composing the cushion atpoints outside of the margin of the matrix, the escape being sufficientto remove the moisture as fast as it leaves the matrix withoutmaterially reducing the pressure of the cushion thereon.

In the application of this improved process l make use of an improvedapparatus, which I will now specifically describe.

In the drawings, P represents the dryingbed usually employed in dryingthe matrices.

A represents a hollow metallic air-chamber, of sufficient size to coverthe matrix when placed upon the bed. This chamber may be raised orlowered for the introduction or removal of the matrix by means of thescrew S, attached to the wheel W.

D represents an induction-pipe for the introduction of dry compressedair from proper compressing apparatusnto the chamber A to form a cushionof air pressing equally upon i 'all parts of the outer surface of thematrix.

c c c are eduction-orifices in the sides of the chamber to allow alimited escape of the air outside of the margin of the matrix. Theseorifices, while s ufficiently large for the purpose intended, are notlarge enough to diminish materially the pressure of the compressed airupon the matrix. r

It is obvious that these orifices may be o the form shown, or maybesimple notches cut in the lower edge of the sides of the chamber; orslight elevations might be made on the surface of the bed, so as toprevent the chamber from fitting closely in every part, and thus leave asmall vent for the escape of the compressed air, without departing fromthe spirit of my invention.

To prevent undue pressure in any event upon the sides of the chamber orupon its top, the safety-valve S' is attached.

In operation the drying-bed P is heated by the introduction of steaninto its nterior, or by any other suitable means. The chamber IOO A israised and the matrix placed upon the surface of the bed. The chamber isthen lowercd and dry compressed air forced into it through theinduction-pipe D. The compressed air forms a cushion, pressing evenlyupon the matrix in every part and maintaining it firmly upon thedrying-bed and preventing it from warping in the process of drying. Theheat of the bed causes the rapid evaporation of the noisture in thematrix, which moisture is removed by the limited escape ot' the air, asabove described. In this manuer the matrix may be dried in a very shorttime and more perfectly than by the ordinary method, while the entireoperation is much simpler and more convenient than that usuallyemployed.

In the method heretofore employed it is necessary to place the matricesupon the heated bed before removing them from the forms. The heat isfound to be injurious to the types, causing them to adhere and requiring them to be knocked apart before they can be distributed, and sorendering them liable to become misshapen. The alternate heating andcooling to which the type is subjected in repetitions of the dryingprocess also seriously impairs its durability.

By my improved process above described, and by the use of my improvedapparatus, it is possible to dry the matrices after they have beenremoved from the forms as well as before removal, thus preventing theinjury to the type ordinarily incurred.

The compressed air introduced into the chamber may be either hot orcold; but as hot air will materially facilitate the drying process, Iprefer its use.

Though primarily intended for drying the matrices used in castingstereotype-plates, my invention is equally applicable for drying anyarticle formed of plastic material molded while wet, and which isrequired to be contined upon a rigid bed, either flat or of other form,while being dried. i

I an aware that in drying the gummed bac-ks of postage-stamps a currentof warm air has been forced by a rotating fan upon the gummed surfacebut I am not aware that in any apparatus of this nature a cushion ofcompressed air has ever been confined over the sheet to be dried so asto press uniformly on all parts of its outer surface and prevent it fromwarping during the drying operation. Such a pressure is of the firstimportance in drying matrices.

Having thus described my invention, what I claim is- 1. The method ofholding a matrix while it is being dried, consisting in supporting thematrix upon a rigid bed and applying to its outer surface a cushioncomposed of compressed air, which is supplied by a suitable compressingapparatus, and is confined over the matrix to exert a uniform pressureon the entire outer surface of the latter and prevent it from warping,as set forth.

2. The method of holding a matrix and conducting moisture therefrom,consistin g in supporting the matrix upon a rigid bed and applying toits outer surface a cushion composed of compressed air, which issupplied by a suitable compressing apparatus, and is confined over thematrix to exert a uniforn pressure on the entire outer surface of thelatter, and is allowed to escape at points outside ot' the margin of thematrix sufliciently to carry ofi' the moisture from the matrix withoutmaterially reducing the pressure of the cushion thereon, as set forth.

3. As a means for applying a cushion of compressed air to a matrix, thecombination of the matrix-supporting bed and the movable chamber open onthe side adjacent to the bed,

and provided with an induetion-pipe communicating with a suitableair-compressing apparatus.

4. The hollow metallic air-ch amber A, pro vided with an induction-pipe,D, and an eduction orifice or orifces of smaller capacity than theinduction-pipe, in combination with a heated bed, P, for subjecting thenatrices used in casting stereotype-plates to a continuous current ot'compressed air, substantially in the manuer and for the purpose setforth.

In testimony whereof I have signed my name to this specificatiou, in thepresence of two subscribing witnesses, this 27th day of March, A. D.1880.

- WILLIAM J. JOHNSON.

YVitnesses:

H. Gr. WADLIN, C. F. BROWN.

